This disclosure generally relates to systems for managing the take-up and pay-out of long flexible objects such as cables, ropes and hoses. For the purpose of illustration, systems for managing the take-up and pay-out of umbilical cables for crawling robots will be described.
When using robotic surface-crawling vehicles (hereinafter “robotic crawlers”) in maintenance (e.g., inspection) applications, power and control signals need to be sent to the robotic crawler, and data from on-board sensors, such as non-destructive inspection (NDI) equipment, needs to be sent from the robotic crawler to a command center. In most applications this power and data transfer is handled by an umbilical cable. The umbilical cable may also include a hose that supplies water to the robotic crawler in cases where the NDI equipment comprises one or more ultrasonic transducer arrays that use water as acoustic couplant. The umbilical cable is often heavier than the robotic crawler, which can disrupt the motion of the crawler if the cable weight tension is not relieved, and extra cable length must be kept far enough away from the robotic crawler to avoid entanglements.
Umbilical cable management for robotic crawlers usually involves some type of overhead gantry and track-based system. These can be large and difficult to install in the field and are usually feasible only in fixed locations. Standard ground-based vehicles, like boom-trucks or scissor lifts, have also been used as platforms for cable management, but due to the limited mobility of these types of platforms, they may be unsuitable for use with general-purpose robotic crawlers that have large ranges of motion.
An alternative solution is to use wireless data transmission and on-board power, but that approach has other types of limitations, including: length of time on target, wireless bandwidth, and wireless restrictions in some areas.
In addition, when the robotic crawler is used in situations where it may fall off the target object undergoing maintenance (e.g., inspection), the system should have a fall protection system. One class of fall protection devices for robotic crawlers is safety nets. Nets may work in some situations, but require significant support infrastructure and may be difficult to set up in a manner that provides the desired coverage. Another class of fall protection devices for robotic crawlers is safety tether cables. In some implementations, this safety tether cable may be combined with the power-data umbilical cable. Fall protection systems are currently available for humans, which include: cables and safety lines paid out from overhead superstructure on a building or moved around the object being inspected (e.g., an airplane); and booms with cables and safety lines extended off high lift equipment or other factory equipment.
In order to facilitate the use of remotely operated tool-equipped robotic crawlers, a system for efficiently managing an umbilical cable and protecting the robotic crawler and the environment from fall events is desired.